Usually single-family houses are protected by lightning rods, located on their roofs. But sometimes customers do not want to install any additional elements on the building , in order not to change its exterior. In such cases it is possible to protect the house from atmospheric discharges by detached lightning rods. If the building is two- or three-storeyed, then in order to guarantee reliable protection, the interception rod must be sufficiently high. Recently, the ZANDZ Technical Center was given the task to calculate lightning protection of a single-family house 11 m high without installing lighting rods on it. We proposed a solution using air-terminals masts located at a distance from the house. Let's study it in more detail.
An example of a single-family house lightning protection
Object: single-family house.
Figure 1 - Plan of the object.
Task: Perform calculations of the lightning protection system of a private house using detached lightning rods.
The protection of buildings and structures against lightning discharges is ensured by lightning rods. A lightning rod is a device rising above the facility that diverts lightning current into the ground without entering the facility. It consists of a lightning rod which directly takes the lightning discharge upon itself, a down conductor and a ground electrode.
Solutions to meet the requirements for a private house lightning protection system:
1. Lightning protection is carried out in accordance with IS 153-34.21., 122-2003"Instructions for lightning protection of buildings, structures and industrial communications" (hereinafter IS) and 34.21.122-87 "Instructions for lightning protection of buildings and structures" (hereinafter AD).
2. The object refers to category 3 of lightning protection. System reliability must be not less than 0,9.
3. The lightning protection of the object is made with the help of 2 vertical detached air-terminal masts 14 m high (ZZ-201-014).
4. Installation of a grounding device for each mast, consisting of 2 vertical electrodes with a length of 3 m, connected by a horizontal electrode (copper bonded tape of 30x4 mm). The distance from the horizontal electrode to the foundation of the building is not less than 1 m, the depth is 0.5 - 0.7 meters;
Results of the calculation carried out with the software developed by the JSC "Energy Institute to the name of G.M. Krzhizhanovsky (JSC "ENIN"):
The density of lightning discharges into the ground – 4 strikes / sq. km per year
The total number of strikes into the system is 0.032 (once every 31 years);
The total number of breakthroughs is 0.0013 (once in 769 years);
System reliability - 0,958.
Probability of breakthroughs into all the system objects - 0.042.
Figure 2 shows the arrangement of equipment.
Table 1 gives the list of the required equipment and materials.
Figure 2 - Location of equipment for lightning protection of a single-family house.
Условные обозначения - notations
Молниеприемник мачта высотой 14 м – air-terminal mast 14 m high
Электрод - electrode
Полоса омедненная стальная сечением 30 на 4 – copper-bonded tape with the cross-section of 30 to 4
Table 1 - List of need in materials.
|№||Figure||Product item||Name||Quantity, pcs.|
|1.||ZZ-201-014||ZANDZ Vertical lightning rod 14 m (galvanized steel; with embedded fittings for placing under the foundation)||2|
|2.||ZZ-001-065||ZANDZ Copper-coated threaded grounding rod (D14; 1.5 m)||8|
|3.||ZZ-002-061||ZANDZ Threaded coupler||5|
|4.||ZZ-003-061||ZANDZ Starting tip||4|
|5.||ZZ-004-060||ZANDZ Driving head for a jackhammer||2|
|6.||ZZ-006-000||ZANDZ Conductive grease||1|
|7.||ZZ-008-000||ZANDZ Header for a jackhammer (SDS max)||1|
|8.||ZZ-005-064||ZANDZ Clamp for connecting conductors (up to 40 mm)||8|
|9.||ZZ-007-030||ZANDZ Waterproof tape||2|
|10||GL-11075-20||GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 20 meters)||1|
Do you have any questions about lightning protection of a single-family house? Please contact our ZANDZ Technical center!